These West Coast volcanoes pose 'very high' threat, USGS says

Mike Moffitt

Updated
1:06 pm PDT, Thursday, October 25, 2018

The USGS has completed a new assessment of the threat posed by U.S. volcanoes. The following volcanoes are rated as "very high" threats. (Note: the No. 8 and 9 most dangerous volcanos — Akutan Island and Makushin Volcano in Alaska — are not included due to lack of photos.) less

The USGS has completed a new assessment of the threat posed by U.S. volcanoes. The following volcanoes are rated as "very high" threats. (Note: the No. 8 and 9 most dangerous volcanos — Akutan Island and ... more

Photo: Andrew Richard Hara/Getty Images

Photo: Andrew Richard Hara/Getty Images

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The USGS has completed a new assessment of the threat posed by U.S. volcanoes. The following volcanoes are rated as "very high" threats. (Note: the No. 8 and 9 most dangerous volcanos — Akutan Island and Makushin Volcano in Alaska — are not included due to lack of photos.) less

The USGS has completed a new assessment of the threat posed by U.S. volcanoes. The following volcanoes are rated as "very high" threats. (Note: the No. 8 and 9 most dangerous volcanos — Akutan Island and ... more

Photo: Andrew Richard Hara/Getty Images

These West Coast volcanoes pose 'very high' threat, USGS says

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As if wildfires and earthquakes weren't enough to lose sleep over, people in California, Oregon and Washington can start worrying about volcanoes too.

A new assessment carried out by the United States Geological Survey rated 18 U.S. volcanoes as posing a "very high" threat level. Of those, three are in California, five in Alaska, four each in both Washington and Oregon, and two in Hawaii.

Not surprisingly, Hawaii's Kilauea volcano is currently considered by the USGS as the most dangerous volcano on U.S soil, earning an overall threat score of 263. Kilauea made headlines earlier this year when a series of dramatic eruptions spawned rivers of lava on the Big Island. More than 700 homes and business were destroyed.

On the "very high" threat scale, Kilauea was followed by Mount St. Helens (235) and Mount Rainier (203), both in Washington. Mount St. Helens notoriously erupted in 1980, spewing rock, ash, pumice and 1.5 million metric tons of sulfur dioxide. Fifty-seven people died, the largest volcano-related loss of life in U.S. history.

California's most dangerous volcanoes are Lassen volcano center, the Long Valley Caldera and Mount Shasta.

Volcanologists said earlier this year that the Long Valley Caldera sits on a reservoir of semi-molten magma measuring a 240 cubic miles. If it were to erupt, it would make the Mount St. Helens eruption seem like a firecracker by comparison. Mount St. Helens released a mere 0.29 cubic miles in 1980.

The USGS National Volcanic Threat Assessment, released this week, is the first since 2005. A total of 161 volcanoes were evaluated. (The most dangerous are shown in the above slideshow.)

"The threat ranking is not an indication of which volcano will erupt next," the report stated. "Rather, it is an indicator of the potential severity of impacts that could result from future eruptions at any given volcano."

The report raises the threat level for 12 volcanoes and reduces or removes it for 20.